From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751904AbdFHPsO (ORCPT ); Thu, 8 Jun 2017 11:48:14 -0400 Received: from smtprelay0077.hostedemail.com ([216.40.44.77]:51509 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751827AbdFHPsM (ORCPT ); Thu, 8 Jun 2017 11:48:12 -0400 X-Session-Marker: 6A6F6540706572636865732E636F6D X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,joe@perches.com,:::::::::::::::::::::::::::::::::::::::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1373:1431:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:1960:1963:2393:2553:2559:2562:2828:3138:3139:3140:3141:3142:3354:3622:3865:3866:3867:3868:3870:3871:3872:3874:4321:5007:6742:7514:7903:10004:10400:10848:11232:11658:11914:12043:12296:12740:12760:12895:13069:13161:13198:13229:13255:13311:13357:13439:14096:14097:14181:14659:14721:21067:21080:21433:21627:30054:30060:30090:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:3,LUA_SUMMARY:none X-HE-Tag: quilt00_81309210a750c X-Filterd-Recvd-Size: 3710 Message-ID: <1496936886.1929.20.camel@perches.com> Subject: Re: [PATCH v1 04/25] lib/vsprintf: Print time and date in human readable format via %pt From: Joe Perches To: Arnd Bergmann , Andy Shevchenko Cc: Andy Shevchenko , Rasmus Villemoes , Greg Kroah-Hartman , Andrew Morton , Linux Kernel Mailing List , Alessandro Zummo , Alexandre Belloni , linux-rtc@vger.kernel.org, Bartlomiej Zolnierkiewicz , Dmitry Torokhov , Geert Uytterhoeven , Guan Xuetao , Ingo Molnar , Jason Wessel , Jonathan Corbet , Jonathan Hunter , Krzysztof Kozlowski , "Rafael J. Wysocki" , Thierry Reding Date: Thu, 08 Jun 2017 08:48:06 -0700 In-Reply-To: References: <20170608134811.60786-1-andriy.shevchenko@linux.intel.com> <20170608134811.60786-5-andriy.shevchenko@linux.intel.com> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.22.6-1ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2017-06-08 at 17:33 +0200, Arnd Bergmann wrote: > On Thu, Jun 8, 2017 at 4:55 PM, Andy Shevchenko > wrote: > > On Thu, Jun 8, 2017 at 5:49 PM, Arnd Bergmann wrote: > > > On Thu, Jun 8, 2017 at 3:47 PM, Andy Shevchenko > > > wrote: > > > > There are users which print time and date represented by content of > > > > struct rtc_time in human readable format. > > > > > > > > Instead of open coding that each time introduce %pt[dt][rv] specifier. > > > > > > I really like the idea, and the implementation seems fine for this use case, but > > > before we reserve %pt for rtc_time, could we discuss whether we want > > > that for printing struct tm, struct timespec64, time64_t or ktime_t instead? > > > > How many users? > > It's hard to predict, I would assume we get more users once there is an > easy way to print the time. > > > For struct tm it's somelike 4 (which want to print its content). > > Good point. I notice that they all convert from time64_t or time_t into > struct tm immediately before printing it, so we can scratch that one > as long as there is a way to pretty-print a time64_t. We also don't > need to print a time_t as we want to kill that one off anyway. > > If we only care about printing time64_t and rtc_time, we can easily > use %pT for one and %pt for the other, but there may still be good > reasons to print a timespec64 or ktime_t. > > > I can see good reasons for pretty-printing any of them, but the namespace for > > > format strings is rather limited. The kernel already uses different types for the same leading letter. For instance: %pI4 vs %pI6, %pap vs %pad A single 't' letter could do reasonably well.